New York may be the city that put the controversial police practice known as "stop and frisk" on the nation's radar — but Chicago officers are initiating these encounters four times more frequently than New York did at the height of its practice in that city in 2011, according to a report released yesterday by the American Civil Liberties Union (ACLU).

The Illinois branch of the group, which issued the report, also found that black residents accounted for nearly three quarters of police stop and searches in Chicago — a disproportionate figure given only just over a third of the city's population is African American.

The study found that in 2014, an average of 93.6 out of every 1,000 Chicago residents were stopped and frisked. In comparison, only 1.6 New York residents were stopped in that same year, while that number reached 22.9 at the peak of the practice in New York in 2011, before widespread criticism led to a review by a federal judge who ruled it unconstitutional. In the summer of 2014 alone, Chicago police stopped more than 250,000 people without arresting them, the report found.

"While most of the media coverage has suggested that that stop and frisk was a New York phenomena — it's misuse is not limited to New York," Harvey Grossman, legal director for the ACLU of Illinois, said in a statement accompanying the report. "Chicago has been systematically abusing this practice, for reasons that are not justified by our Constitution."

"Just like New York, we see that African Americans are singled out for these searches," he added.

The disproportionate police targeting of African Americans is highlighted by such figures in the report, which revealed that in neighborhoods like Chicago's Jefferson Park, black residents make up only 1 percent of the population, but account for 14 percent of all stops, the ACLU said.

The report also highlighted problems in the reporting process: in every police report card on stops in Chicago that researchers examined, officers failed to provide sufficient reasons to legally justify the stop — often offering explanations "unrelated to a suspicion of a crime" instead.

The police department failed to address this issue, and has not provided adequate training to its officers, the report charged.

A spokesperson for the Chicago Police Department (CPD) rejected the accusation of racial bias and told VICE News via email that the department has been working to improve training.

"Our chief goal is to ensure that everyone in every neighborhood enjoys the same sense of safety, and the best way to achieve that goal is working with the communities we serve," the spokesperson wrote. "That's why community policing and building trust with residents is the foundation of our policing philosophy. People should only be stopped based on crime data and crime information. Nothing else."

Following a landmark Supreme Court decision in 1968 permitting officers to conduct stop and frisk searches if they have reasonable suspicion that a person has or is about to break the law, officers in New York and around the country have carried out the same or similar-type searches. For the people that are subject to it — a huge majority of whom are never charged with a crime — the experience has often been described as humiliating, invasive, and discriminatory.

"What this data shows should be a wake-up call for residents of the city," Karen Sheley, the ACLU's senior legal counsel and one of the authors of the report, said in a statement. "CPD is engaging in wholesale stop and frisks of African American youth, without any link to criminal activity in most cases."

"These stops don't make us safer, they simply drive a wedge further between the police and the public they serve," she added.

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